Originally Posted by Velo Dog
Friend of mine who switched to discs this spring says the same thing: "They work about as well and weigh a pound more." He doesn't have any complaints about their performance, but they're not an improvement over his old Ultegras w/aftermarket pads and they do weigh more.
I have two mountain bike solos, and they both have V Brakes fitted. They are completely adequate for my type of use, and I also do Road rides at a respectable speed when I fit the Slicks. They do not need or require disc brakes, but then I am an accomplished rider and I only weigh 147lbs.
However, there are mountain bikes, that in my opinion need disc brakes, These are the higher quality Full suspension bikes, and the way these things shift on the flat offroad, or when Gravity takes over, disc brakes are well worth the expense, but these bikes probably came with top grade Hydraulic disc brakes as standard. On the average Hardtail or medium quality full suspension bikes that will go slower downhill, then V Brakes are good enough
Now we get onto the beastie. A full offroad Tandem. This bike is heavy, it is fast and takes a lot of stopping. Top quality Disc brakes, massive great big discs and a pleading letter to the bank manager to get them.
Disc brakes have several advantages. The braking area is out of the trail debris and wet and mud and the braking effect is better than any rim brake. They do not wear out rims that ordinary brakes will do, and disc replacement is cheaper than Rim replacement. Disadvantages-- Heavy, expensive, and you do have a bit of rub.
On a bike that is mainly used on the road, the weight and pad rub will put you at a disadvantage. However- If you are talking Offroad, full suspension, Clydesdale, or wet muddy weather they are a godsend.
As to disc brakes not being better than V Brakes- They are providing a good quality Hydraulic unit is fitted. Cable disc brakes are often not as good as V Brakes, and the cheaper Hydraulic units may take some sorting to get right.